Ore Genesis and Geochemical Characteristics of Carbonate-Hosted Talc Deposits in Nangarhar Province, Afghanistan

Muhammad Tahir, Akira Imai, Ryohei Takahashi, Shujiro Yano

Research output: Contribution to journalArticle

Abstract

Talc deposits in Nangarhar Province, are hosted by Paleoproterozoic carbonate rocks, metamorphosed to amphibolite facies in the east–west (E–W) trending Spinghar Fault Block. Many deposits in this province have potential economic importance. However, detailed geologic and petrological studies on ore genesis are still lacking. In this study, eight talc deposits and two prospects of the Spinghar Fault Block were investigated. Talc is mainly formed by alteration of the host dolomite marble, magnesite rocks, and tremolitite. Talc ore bodies occur parallel to subparallel to the beddings of the host carbonate rocks. Dolerite occur as dikes and sills and are mostly metamorphosed to amphibolite. Although the amphibolite occurs mostly parallel to subparallel to the beddings of the host carbonate rocks, and talc orebodies, it partly crosscuts the host rocks. Massive layers of tremolitite were observed with most of the talc ore bodies. Quartz veins occur along the gneissosity of gneiss all over the study area. SiO2 and MgO content in talc rocks from all deposits ranged from 49.1 to 65.1 wt% and from 26.1 to 32.9 wt%, respectively. CaO content in talc rocks and magnesite rocks are less than 1 wt%. ƩREE content in talc rocks ranged from 0.1 to 8.9 ppm. Chemical compositions of host carbonate rocks are close to the ideal composition. Concentrations of Al, Ta, Hf, Zr, Th, Cr, Ni, Co, and ƩREE in talc ores and host carbonate rocks were very low and inconsistent with mafic and ultramafic rocks protolith. Therefore, the metamorphosed sedimentary carbonate rocks were likely to be the protolith of the talc ores. The occurrence of parallel to subparallel quartz veins to the gneissosity of gneiss, as well as the presence of hydrous minerals in host carbonate rocks, suggested that hydrothermal fluids were most probably supplied through the gneiss.

Original languageEnglish
Pages (from-to)352-372
Number of pages21
JournalResource Geology
Volume68
Issue number4
DOIs
Publication statusPublished - Oct 1 2018

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Talc deposits
Carbonates
talc
Ores
Talc
Rocks
carbonate
carbonate rock
host rock
gneiss
magnesite
rock
ore body
quartz vein
amphibolite
protolith
Quartz
rare earth element
province
ore

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Cite this

Ore Genesis and Geochemical Characteristics of Carbonate-Hosted Talc Deposits in Nangarhar Province, Afghanistan. / Tahir, Muhammad; Imai, Akira; Takahashi, Ryohei; Yano, Shujiro.

In: Resource Geology, Vol. 68, No. 4, 01.10.2018, p. 352-372.

Research output: Contribution to journalArticle

Tahir, Muhammad ; Imai, Akira ; Takahashi, Ryohei ; Yano, Shujiro. / Ore Genesis and Geochemical Characteristics of Carbonate-Hosted Talc Deposits in Nangarhar Province, Afghanistan. In: Resource Geology. 2018 ; Vol. 68, No. 4. pp. 352-372.
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